(1.) Field of the Invention
The present invention relates to the processing of sheet material and particularly to the removal of waste edges from punched paper board blanks which have been stacked. More particularly, this invention is direct to apparatus for removing waste edge pieces which have been at least partly severed by stamping or punching blanks from sheet material and especially to such apparatus which is movable relative to stacks of such blanks to remove the waste edges sucessively layer-to-layer. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2.) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in the removal of waste edges from paper board blanks which are to subsequently be formed into boxes. As its well known, the blanks from which cardboard boxes are formed are punched from sheet material using steel line tools. The individual blanks, which are known as cut-outs, together with the waste grid are stacked on pallets. The removal of the waste edge pieces from the stack is still frequently performed manually. This is an extremely laborious procedure which involves a high outlay of energy and time.
An example of prior apparatus which may be employed for the mechanical i.e., semi-automatic, removable of waste edges from punched blanks may be seen from published German patent application Ser. No. 2,283,184. This prior apparatus employs a plurality of milling cutters supported from a movable frame. In order to remove the waste edges, the frame is moved downwardly along the vertical side of a stack of punched blanks with the cutter positioned relative to the stack so as to engage the waste strips or edges. Prior apparatus of the type disclosed in German application No. 2,283,184 is characterized by a number of inherent deficiencies. Thus, by way of example, the milling cutters actually destroy the waste strips and, and in so doing, produce considerable dust and a high level of noise. Further, as a result of the relatively large diameter of the cutters themselves, the prior apparatus has limited utility, i.e., the prior apparatus can not be employed to remove very narrow waste strips. Furthermore, the forces exerted by the milling cutters of the prior apparatus are frequently insufficient to separate the waste edges from the blanks, this particularly being true in the case of cardboard having a smooth surface and a high gram weight. Additionally, the milling cutters have a comparatively short useful life and thus, when employing the prior apparatus, it is necessary to interrupt production at relatively short time intervals in order to change the cutters. It should also be noted that, since the cutters are driven at a very high speed, there is an inherent risk of injury to operating personnel.